1. Technical Field
The present disclosure relates to a method of forming hardmask patterns and to a method of forming fine patterns of a semiconductor device, and more particularly to a method of forming fine pitch hard mask patterns while using double patterning to overcome a resolution restriction of the exposure facility.
2. Description of the Related Art
To fabricate highly integrated semiconductor devices, one typically needs highly miniaturized patterns. For example, to integrate many elements within a small area, the individual elements should be smaller. The smaller dimensions may be obtained by reducing the pitch of the pattern. The pitch of the pattern is the sum of the width and the gap between adjacent patterns. However, with the significant decrease of design rules of semiconductor devices, a limit in forming patterns with a fine pitch may have been reached due to resolution restrictions of photolithography processes. The resolution restrictions of photolithography are especially significant when forming an isolation region that defines an active region in a substrate, and when forming a line and space pattern (hereinafter referred to as “L/S pattern”).
To overcome the resolution restrictions of photolithography, spacers with a fine feature size have been formed on both side surfaces of one pattern, and a spacer pattern formed according to the spacers has been used as a hardmask, to pattern a film by etching. However, when the spacer pattern is used as a hardmask, a pair of right and left spacers formed on the sides of one reference pattern may become uneven. Generally, the spacers are made thicker than their desired thickness to ensure an even thickness of the right and left spacers. As a result, it may become difficult to remove the spacers after using them as a hardmask. Also, a hard mask in the form of the spacer is typically centered around the pattern to surround the pattern. Therefore, when a line pattern is formed using the spacers, separate trimming is required to separate the spacers as an individual line pattern.
Thus, there is a need for a method for forming fine pitch hard mask patterns and forming fine patterns of a semiconductor device using the same which overcomes the resolution restrictions of photolithography.